Bull horn circuit diagram, usually used for truck, very big truck..
The audio signal source is fed to pin 3 of U1, an LM386 low-voltage amplifier, through C3 and R1. Potentiometer R1 sets the drive or volume level. U1, which serves as a driver stage, can be set for a gain of from 20 to 200. The output of U1 at pin 5 is fed to U2 -a 377 dual two-watt amplifier connected in parallel to create about four watts of output power-at pins 6 and 9 via C4 and C5.
Frequency balance is determined by R2, R4, and C10 on one side, and also the corresponding parts R6, R5, and C9 on the other side. The output of the two amplifiers (at pins 2 and 13) are capacitively coupled to SPKR1 through C6 and C7.